The present invention relates to the use of a feeder insert, having a volumetric center of gravity which is offset in relation to the opening axis of the passage opening of said feeder insert, in the manufacture of a casting mold having a vertical mold separation and a feeder insert which for dense feeding of the mold cavity during the casting procedure is attached to the casting mold. The invention furthermore relates to a method for manufacturing a casting mold having a vertical mold separation and a feeder insert which for dense feeding of the mold cavity during the casting procedure is attached to the casting mold. The invention also relates to corresponding casting molds and feeder inserts.
Feeder systems with one or multiple parts are employed in large numbers and varieties in casting metals in casting molds. The feeder systems, also referred to as feeders, used are largely surrounded by a molding material, such as molding sand, which is used to manufacture the casting mold, and on account thereof held in a position in relation to the mold cavity in the casting mold. Known feeders have a feeder cavity having a passage opening for the liquid metal, on account of which there is a connection between the mold cavity and the feeder cavity. On account thereof, a partial amount of the metal which during the casting procedure is filled into the mold cavity of the casting mold enters the feeder and thus the feeder cavity. During the solidifying procedure which is associated with contraction of the cast metal, the liquid metal which is located in the feeder system should be able to flow back into the casting mold, so as to there equalize or compensate for the shrinkage of the casting down to the solidus temperature, respectively.
For this purpose, the metal which has made its way into the feeder insert is kept in the liquid state for as long as until the metal which is present in the interior of the casting mold has solidified or has partially solidified to form the casting. Therefore, at least part of the feeder insert is usually composed of an insulating and/or exothermal material. Exothermal materials have the property of being ignited on account of the high temperatures which prevail when liquid metal enters into the feeder cavity of the feeder insert. From this point in time on, an exothermal reaction is automatically performed within the material of the feeder insert, so that thermal energy is released over a certain period of time to the metal which is located in the feeder cavity. The metal in the feeder system and in the transition region to the mold cavity of the casting mold is thus kept in the liquid state.
Requirements pertaining to productivity have been significantly increased also in the foundry sector, leading to the search for possibilities for automating the manufacture of molds and for the manufacture of casting molds for castings in large volumes to be designed in a more efficient manner. For this purpose, automated vertical greensand molding plants (for example Disamatic molding machines by DISA industries A/S) have been developed. These molding machines have two pattern halves, of which a first pattern half is mounted on a press piston which is adjustable exclusively in a linear manner and the second pattern half is mounted on a pivotable mold plate, which is also referred to as a pivoting plate. The pivotable mold plate may be moved to and fro between a horizontal alignment in which the second pattern half is equipped with a feeder system, and a vertical alignment. In the vertical alignment thereof, which corresponds to the operating position of the pivoting plate, the pivoting plate is displaceable together with the first pattern half, also referred to as the pressing plate, in a manner parallel with the press piston. The pressing plate and the pivoting plate at least laterally delimit a mold chamber into which the molding material for configuring at least one mold half of a casting mold is filled. The filled molding material is subsequently compressed by relative movement between the pressing plate and the pivoting plate, and a mold half or a mold part, respectively, is thus produced. A feeder system which is disposed on the pattern half on the pivoting plate and which during manufacturing of the mold part is thus disposed in the mold chamber, is received within the produced mold part. Such feeder systems by way of longitudinal feeder axis thereof are aligned so as to be approximately vertical to the pivotable mold plate, so that the passage opening of the feeder insert during casting runs in an approximately horizontal manner. In order for the feeder volume to be minimized, known feeder inserts moreover have a volumetric center of gravity which is offset in relation to the passage opening and which during the casting procedure in particular is disposed above the opening axis of the passage opening.
Feeder systems for use in the manufacture of a split-type casting mold are known from publications EP 2 489 450 A1 (DE 20 2011 103 718 U1) and DE 10 2013 209 775 B3. The disclosed assemblies comprise a mold plate and/or a mold pattern and furthermore at least one feeder system having a feeder element and a feeder insert. The feeder element and the feeder insert delimit the feeder cavity for receiving the liquid metal. The feeder element has a first end by way of which the former stands or sits in a usually directly bearing manner on the mold plate and/or on the mold pattern. The feeder element has a passage opening by way of which the connection between the mold cavity of the casting mold and the feeder cavity of the feeder system is guaranteed. The passage opening here is delimited by a side wall of the feeder element.
In order for the forces which during compressing of the molding material which is used for manufacturing the mold part of the casting mold act on the known feeder systems to be able to be absorbed, the side wall around the passage opening according to EP 2 489 450 A1 is configured so as to be deformable. The side wall is deformable in such a manner that a reduction of the spacing between the first end of the feeder element and the second end of the feeder element to which the feeder insert of the feeder system is fastened by way of a fitting element on the feeder element results. This results in an overall reduction of the total height of the feeder system.
Alternatively, it is proposed according to DE 10 2013 209 775 B3 that the feeder element and the feeder insert are configured so as to be mutually displaceable. In this way, the compression force which is created during compression of the molding material is compensated for also in this known feeder system by pushing together the feeder system in a manner vertical to the opening axis of the passage opening.
One disadvantage which may arise in some cases when using the known feeder systems is caused by the passage opening which is offset in relation to the volumetric center of gravity of the feeder system and by the side wall which delimits the passage opening and which sits on the first end of the feeder element on the mold plate. The side wall, which serves as a placement face of the feeder system on the mold plate or on the mold pattern, is likewise disposed so as to be offset in relation to the volumetric center of gravity of the feeder cavity, so that a force which acts in the direction of the opening axis of the passage opening during compressing of the molding material produces a tilting moment in the region of the placement face. Especially in the case of high compression pressures in the mold chamber, the feeder system may slightly tilt, so that the placement face at the first end of the feeder element bears in a non-uniform manner on the mold plate or on the mold pattern. In this way, reliable sealing in the transition region between the feeder and the mold cavity may in some instances no longer be guaranteed, and disadvantages may arise during the casting procedure, for example entry of molding material into the mold cavity or configuration of an untidy breaker edge which is to be configured on the transition between the casting and the feeder.